1. Field of the Invention
The present invention relates to plasma display panels generally, and more particularly, to plasma display panels producing an enhanced luminous efficiency.
2. Description of the Related Art
Recently, cathode-ray tube display devices have been replaced with plasma display panels in many applications. In a plasma display panel, discharge gas fills the void created between two substrates bearing a plurality of electrodes, and a discharge voltage is applied to the electrodes in order to generate ultraviolet rays. The ultraviolet rays excite phosphor layers formed in a predetermined pattern to form a variable visible image, corresponding to signals applied to drive the panel.
A plasma display panel includes a rear substrate and a front substrate facing each other. A plurality of address electrodes are arranged on an inner surface of the rear substrate. Barrier ribs are formed between the front substrate and the rear substrate to define discharge cells. Phosphor layers are coated on the surface in the discharge cells. Pairs of sustain electrodes crossing the address electrodes are formed on an inner surface of the front substrate. One of the pairs of the sustain electrodes is a X electrode, and the other is a Y electrode.
In the plasma display panel, discharge cells to emit light are selected by address discharge that is generated by applying an address voltage between the address electrodes and the Y electrodes, and the selected discharge cells emit light through sustain discharges generated by applying a sustain voltage between the X electrode and the Y electrode. A discharge gas that fills the discharge cells emits ultraviolet rays in response to the sustain discharge, and the ultraviolet rays make the phosphor layers emit visible rays. The visible light emitted from the phosphor layers forms an image on the plasma display panel.
There are requirements to increase luminous efficiency of a plasma display panel. The plasma display panel should have a large space for generating a sustain discharge which excites a discharge gas, a large surface area of phosphor layer, and fewer structures which interfere with the visible rays emitted from the phosphor layer.
Improving luminous efficiency of a plasma display panel, however, has been a difficult issue. The space for generating the sustain discharge is small, and only a small portion of the phosphor layer contributes to generate visible rays, because the sustain discharge is generated only in a narrow area between the X electrode and the Y electrode. Furthermore, a portion of visible rays emitted from the phosphor layer is absorbed or reflected by other structures formed in the plasma display panel such as a protective layer, dielectric layers, and sustain electrodes. A large amount of the visible light transmitted through the front substrate is thus wasted through interference with other structures. It is therefore one object of the present invention to provide a plasma display panel exhibiting greater luminous efficiency.